How to check whether a variant array is unallocated?

Chip Pearson made a useful module called modArraySupport that contains a bunch of functions to test for things like this. In your case, you would want to use IsArrayAllocated.

Public Function IsArrayAllocated(Arr As Variant) As Boolean

This function returns TRUE or FALSE indicating whether the specified array is allocated (not empty). Returns TRUE of the array is a static array or a dynamic that has been allocated with a Redim statement. Returns FALSE if the array is a dynamic array that has not yet been sized with ReDim or that has been deallocated with the Erase statement. This function is basically the opposite of ArrayIsEmpty. For example,

Dim V() As Variant
Dim R As Boolean
R = IsArrayAllocated(V)  ' returns false
ReDim V(1 To 10)
R = IsArrayAllocated(V)  ' returns true

The technique used is basically to test the array bounds (as suggested by @Tim Williams) BUT with an extra gotcha.

To test in your immediate window:

?IsArrayAllocated(Result)

Testing in Watch window: there are may ways to do this; for example, add a watch on R and under "Watch Type" select "Break When Value Changes".

To avoid error handling, I used this, seen on a forum long time ago and used sucessfully since then:

If (Not Not Result) <> 0 Then 'Means it is allocated

or alternatively

If (Not Not Result) = 0 Then 'Means it is not allocated

I used this mainly to extend array size from unset array this way

'Declare array
Dim arrIndex() As Variant        

'Extend array
If (Not Not Result) = 0 Then
    ReDim Preserve Result(0 To 0)
Else
    ReDim Preserve Result(0 To UBound(Result) + 1)
End If